An exemplary embodiment of this application relates to a stapler in a finishing device having a variable start pulse that communicates information on the sets of sheets or jobs to be stapled by the stapler. More particularly, the exemplary embodiment relates to a stapler having a variable start pulse for use in a finishing device that receives sets of sheets from an associated document creating apparatus, such as a copier or printer. An end user causes the variable pulse to be generated by inputting job parameter information at the control panel of the document creating apparatus. The duration of the variable start pulse is detected by the stapler and used to select a stapling cycle or algorithm from the various stapling cycles stored in the memory of the stapler that is suitable for both the thickness and media of the sets to be stapled.
As well known in the stapling industry, office copiers and printers may have sorters or finishing stations for sorting sheets received therefrom into collated sets and such collated sets may be automatically stapled in the sorter trays. The trays may also be shifted to a stapler as disclosed in U.S. Pat. No. 4,925,171. The sets may be partially removed from the trays, stapled and returned to the trays, or the sets may be transferred to a stapler as disclosed in U.S. Pat. No. 4,361,373. In all of these staplers, the stapler drives a staple into a set of sheets of some maximum number of sheets or thickness and the same stapler force is used even when a lesser number of sheets or a set of sheets having a lesser thickness is stapled.
As a result, the stapling force imparted is identical for stapling jobs whether the set to be stapled consists of many sheets or only a few sheets. Thus, the extra energy required to assure a thick set of sheets is successfully stapled results in a higher wear rate when only thin sets of sheets are stapled.
Many finishing devices and sheet stacking devices are known in the sheet handling equipment industry, involving collating or stacking of sheets into sets of sheets and finishing each set of sheets by stapling or binding prior to depositing the finished sets of sheets on a collection tray. U.S. Pat. No. 4,864,350 discloses that sheets entering a finishing device may be counted and the stapler disabled if the count is outside of a range of sheets, so that single sheets or sets of sheets exceeding the capacity of the stapler cannot be stapled.
U.S. Pat. No. 4,421,264 discloses a stapler for fastening variable thickness documents. A sensing device coupled to the stapler generates control pulses indicative of the relative motion between the head or hammer assembly and the clinching or anvil assembly of the stapler. A controller processes the pulses and generates control signals which vary the head assembly stroke and the force driving it. By measuring the distance that the head assembly travels from its home position until it contacts the stack of sheets to be fastened, the thickness of the stack can be determined. In addition, the force of the motor that drives the head assembly may be adjusted as a function of the stack thickness.
U.S. Pat. No. 5,161,724 discloses a stapling device for a stack of sheets having a movable staple head that presses an edge of the stack of sheets upwardly against an abutment. If a cam actuated arm having a lug is prevented from contacting an electrical contact on a fixed support above the stack of sheets, an electrical circuit is not completed and the stapled head is not actuated. If the thickness of the stack of sheets does not exceed the maximum thickness that may be stapled, the lug on the cam actuated arm will contact the electrical contact, thus completing the electrical circuit and enabling the staple head to staple the stack of sheets.
U.S. Pat. No. 5,230,457 discloses a sheet stapling device having a current sensor to detect the current load of the electric motor which drives the stapling device. The current sensor generates a signal during the stapling operation. A generated signal that is below a predetermined level indicates no staple is dispensed, and a signal that is above the predetermined level indicates a malfunction or jam or there are too many sheets to be stapled.
U.S. Pat. No. 5,354,042 discloses a sheet sorter having a stapler for stapling sets of sheets in the sorter bins. The stapler is actuated by an electric motor to which the applied power is varied depending upon the number of sheets in the sets and, thus, the thickness of the sets to be stapled. An optical sensor counts the sheets per tray. The purpose of the counting function is to enable the sorter microprocessor to control the power applied to the stapler motor. Since the force by which staples are applied to the sheets in the trays is a function of the level of electric power supplied to the stapler motor, the programmable power supply is capable of increasing or decreasing the applied motor power depending upon the number of sheets counted by the optical sensor.
U.S. Pat. No. 6,216,935 discloses a powered stapler having a solenoid as a driver for a spring biased armature with a stapler head at one end that confronts the stapler anvil. Activation of the solenoid overcomes the spring force and drives the stapler head towards the anvil. In the non-energized condition, the armature may be adjusted relative to the solenoid and the force exerted by the solenoid is varied as a function of the position of the armature with the solenoid. In one embodiment, a sensor mechanism is provided that shifts the position of the armature within the solenoid in accordance with the thickness of the sheets to be stapled.